In 2004 conservation groups co-ordinated by the legal environmental organisation Climate Justice filed similar petitions on behalf of the Sagarmatha National Park in the Himalayas, the Belize Barrier Reef, and Huascaran National Park in Peru.

The Sagarmatha petition is supported by Everest pioneer Sir Edmund Hillary, who said: "The warming of the Himalayas has increased noticeably over the last 50 years... this has caused several and severe floods from glacial lakes, and much disruption to the environment and local people."

In July, Unesco, the UN cultural and scientific agency which manages the World Heritage Convention, announced the establishment of a commission to examine the cases.

It is due to report later this year.

Since then, other legal actions have been initiated against the US over the impact of climate change on Inuit peoples living in the Arctic, and on two species of coral.